Percussive tool



W. A. SMITH.

PERCUSS WE TOOL.

APPLICATION FILED APR 19, 1918.

f 55,175. Patented Oct. 12,1920.

IN V EN TOR.

WA/ ATTO NEYS.

UNITED STATES PATENT orrtca WILLIAM A. SMITH, or EASTON, rnnnsrnvnivra,r-issrsnoa ro INGEBSQLL-RAEZ) COMPANY, OF JERSEY CITY, NEW JnRsn'r, aoonrcnnriou or new JERSEY.

PERCUSSIVE TOOL.

Application filed April 19,

To all whom it may concern:

Be it known that I, WILLIAM A. SMITH, a citizen of the United States,residing at Easton, in the county of Northampton and State ofPennsylvania, have invented a certain new and useful Improvement inPercussive Tools, of which the following is a specification.

This invention relates to percussive tools I and in particular to apercussive tool of the differential piston type adapted for harnmerdrills.

The objects of the present invention are to provide a fluid operatedpercussive tool 1n which the piston is reciprocated forwardly andbackwardly by means of fluid pressure supplied intermittently to threepressure surfaces, two operating to thrust the piston forwardly and oneoperating to return it; a further object being to provide conduits forsupplying the fluid to the three pressure surfaces which will supply thefluid at the proper points of the travel of the piston, and which willquickly supply maximum pressure to the pressure areas so that the hammerdrill will operate efficiently and strike a heavy powerful blow at theend of its forward stroke.

With these and other objects in view, I have devised the construction aspecific embodiment of which is represented in the accompanying drawingsand set forth in the following specification:

In the drawings annexed hereto and formin a part hereof:

I igure '1 shows a cross sectional view of a hammer drill made inaccordance with the present invention in which the piston is shown atapproximately midstroke, and

Fig. 2, shows a similiar view of the hammer drill with the piston instriking position at the end of its forward stroke.

Referring more particularly to the drawings, the cylinder is shown at 1having a large central bore 2 and a smaller bore 3 at its rear end, andin which reciprocates a piston 1. The piston 4 is shown of thedifferential type having a central head 5 and shanks extending fromeither side face thereof, respectively, 6 and 7. As shown in thedrawings, the piston is symmetrical and therefore reversible but thisfeature forms no part of the present invention, but my present inventionis adapted to this form of piston. The fluid supplied to theSpecification of Letters Patent. Pgmj gnt d 0 1; 12 ggqp 151%. SerialNo. 229,622.

tool is admitted at 8 and through the short condult or supply passage 9to an annular recess 10 cut into the smaller bore 3 of the cylinder 1.Another annular recess 11 cut into the smaller bore 3 of the cylinder 1is connected to a conduit 12 which opens into the rear end of thesmaller bore 8 at 13 and also into the rear end of the larger bore 2 asshown at 14. From the above it will be seen that conduit 12 provides apassage for admitting fluid to portions of the cylinder 1 to exertpressure against two pressure areas of thepiston to drive the piston 4forwardly.

A conduit 15 is further provided intercepting the smaller bore 3 at 16and the larger bore 2 at 17 which will provide a passage for supplyingfluid to return the piston to its rearward position. To open connectionbetween the fluid supply 8 and the conduits 12 and 15, the shank 6 ofthe plston 4: is provided with a neck or reduced portion 18. In theposition shown in Fig. l of the drawings the neck portion 18 is shown inits position to open the conduit 12 to the admission port 10 admittingfluid to force the piston forwardly, while in Fig. 2 is shown theposition of the piston to open the connection between the admision port11 and conduit 15 to return the piston.

For convenience, and to permit the piston 4; to be reversed, an extraneck portion 19 is provided in shank 7 to permit the piston at tofunction when in its reversed position. In the position of the piston asshown the neck portion 19 performs no function.

At the forward end of the cylinder 1 is provided the usual front head 20and spacing member 21 within which is located the chuck 22 and withinthe chuck 22 is housed the drill steel 23 which may be rotated with thechuck 22 in any suitable manner, (not shown).

It is to be understood that the present showing and description discloseonly one specific embodiment of the present invention, and that otherforms and modifications are included within the spirit and scope of theinvention, as expressed in th appended claim.

What I claim is:

In a fluid operated percussive tool, the combination of a cylinderhaving bores of different diameters, a fluid conduit extending from apoint in the smaller bore to the forward end of the larger bore, anotherintermediate of the points of connection of the said two fluid conduitswith said smaller 10 bore, a piston in said cylinder having a headfitting the larger bore and a shank fitting the smaller bore, a reducedneck in the rear- Ward portion of saidshank adapted to ali V ternatelyestablish communication between the said supply passage and the saidfluid 1 conduits leading to the ends of the cylinder,

and exhaust means for the cylinder.

In testlmony whereof, I have hereunto set my hand.

WILLIAM A. SMITH.

